<p>Their experience with you as a student… that includes strengths and weaknesses. How you work in a classroom/with your fellow students, your drive, etc. Their job is to help bring your application to life, to make you seem more like the human you are. Therefore, they should try to encompass what they liked about you and what you could work on. Even great recs acknowledge all aspects of a student, and none of us are perfect :-)</p>